The effectiveness of a communication network depends essentially on its network architecture, components and operating conditions. Antennas are critical components in a mobile communication network. A properly chosen antenna can significantly enhance the performance of a mobile communication network.
A phased array antenna (PAA) employs spatially narrow radio frequency (RF) beams to communicate between the network nodes. Electronic beam steering allows the PAA beams to be retargeted instantly after a gap of minimum set-up time for loading the PAA shift registers. In a synchronous link approach the transmit beam of a first PAA is pointed towards the receive beam of a second PAA. Similarly, the transmit beam of the second PAA is pointed towards the receive beam of the first PAA. In the synchronous approach, each node having PAAs can form no more links than the number of beams on its PAAs. Consequently, the network's performance is limited by the number of beams on the PAAs.
Simulations of typical PAA based networks show that for a given spatial distribution of the nodes, the number of links actually available is much smaller than the maximum number of available links. This results in the average packet route going through several node hops, which is very inefficient. Adding more PAAs imposes increased demands of weight, power and physical space. Increasing the number of beams per PAA results in higher cost and thermal load per unit. Therefore, there is a need to implement a PAA based efficient network design.
Synchronous links can be used to implement a backbone of a network. In such an approach, the nodes on the backbone communicate among themselves using long-duration synchronous links. In real world networks, e.g., military networks, a single network backbone is connected to a number of terminal nodes. The backbone to terminal links use short bursts of RF energy in a time division multiple access (TDMA) approach. This requires the backbone nodes to have two sets of PAAs, one set to cover 4π steradian sky for maintaining continuous links to other backbone nodes, and another set to cover 4π steradian sky for TDMA links connecting to the terminal nodes. Two full sets of antennas make additional demands in terms of space, power and weight to accommodate the extra set of antennas. For military aircraft, such demands are prohibitive. Further, the mounting of extra antennas requires additional aircraft fuselage penetrations. Thus, there is a need for a network with a single set of PAAs to communicate with both the backbone and terminal nodes in the network.
In a synchronous link based backbone network, a group of terminal nodes communicating with the TDMA links cannot function as an independent network, i.e., a peer-to-peer network, without connecting to some backbone node. In military environments, a backbone node may not be accessible in some critical circumstances, making the network unavailable. Hence, there is a need for a PAA based network which will allow formation of a network made exclusively of terminal nodes.